Former investor Lewis Barber has filed a lawsuit against BitMEX in the UK High Court seeking £20 million, alleging the exchange offered cryptocurrency derivatives to UK users without Financial Conduct Authority authorization. The claim asserts that BitMEX operated outside regulatory approval while serving British investors between 2018 and 2022. Barber claims he lost Bitcoin worth approximately £20 million trading these unauthorized derivatives during the four-year period. He is now seeking either the return of the lost Bitcoin or equivalent monetary compensation through the legal proceedings.